California’s U.S. senators tend to fall into two categories – headline-grabbers and dependable workhorses for the state’s interests.

For the past 17 years, the state’s two senators have been Dianne Feinstein and Barbara Boxer.

Both elected during the much-heralded “year of the woman,” they have followed the state’s time-honored pattern.

Boxer draws media attention with her quixotic political forays, often involving some left-of-center cause having nothing to do with California, while Feinstein is the go-to person for the state’s economic and political interests.

It explains why voter polls consistently find that Feinstein is among the state’s highest-rated political figures while Boxer’s popularity swings with the tides and rarely reaches beyond the magic 50 percent level.

Every six years, Republicans believe that with just the right candidate and just the right amount of money, they can knock off the woman they love to hate. And they are heartened again by a new poll showing Boxer barely leading the most likely 2010 challenger, former Hewlett-Packard CEO Carly Fiorina.

The Rasmussen Reports poll found that 45percent of California voters support Boxer’s re-election, with Fiorina at 41 percent and 7percent undecided, much closer than a March poll. Fiorina isn’t a declared candidate yet and also would have to defeat Chuck DeVore, a very conservative Republican legislator, for the GOP nomination.

The latest poll, true to form, found Boxer’s overall job approval rating among California voters to be fairly low, with just 21 percent holding a “very favorable” view, down six points from March.

The somewhat negative polling reflects not only Boxer’s historically low approval ratings among Californians but also a couple of recent flashes of publicity, most notably a much-circulated video clip in which she upbraids an Army general for referring to her as “ma’am” and not “senator” during a committee hearing, even though the former is the military equivalent of calling a male senator “sir.”

Boxer is also making waves by chairing the Senate Environment and Public Works Committee’s sessions on global warming in a somewhat imperious manner, drawing criticism, albeit muted, even from Democrats.

Boxer, who has written two novels with a fictional version of herself as the heroine, is characteristically unapologetic for her confrontational style, telling Politico that the publicity “only revs up my people” and helps her raise “millions of dollars because these people are attacking me in the most ridiculous, unfair way.”

Boxer will probably win another term next year, but she’s not a sure bet. If Republicans have a chance to unseat her, it would be with a wealthy, moderate woman – someone like Carly Fiorina.